public static bool IsAssignableFrom(TypeOnStack type1, TypeOnStack type2)
{
// voids aren't assignable
if (type1.IsVoid || type2.IsVoid)
{
return(false);
}
// wildcards match *everything*
if (type1 == TypeOnStack.Get <WildcardType>() || type2 == TypeOnStack.Get <WildcardType>())
{
return(true);
}
if (type1.IsArray && type2.IsArray)
{
if (type1.Type.GetArrayRank() == type2.Type.GetArrayRank())
{
var t1Elem = type1.Type.GetElementType();
var t2Elem = type2.Type.GetElementType();
while (t1Elem.HasElementType)
{
t1Elem = t1Elem.GetElementType();
}
while (t2Elem.HasElementType)
{
t2Elem = t2Elem.GetElementType();
}
if (t1Elem == typeof(WildcardType) || t2Elem == typeof(WildcardType))
{
return(true);
}
}
}
if (type1.IsPointer && type2.IsPointer)
{
if (type1.Type.GetElementType() == typeof(WildcardType) || type2.Type.GetElementType() == typeof(WildcardType))
{
return(true);
}
}
if (type1.IsReference && type2.IsReference)
{
if (type1.Type.GetElementType() == typeof(WildcardType) || type2.Type.GetElementType() == typeof(WildcardType))
{
return(true);
}
}
// any pointer type matches, well, any pointer
if (type1.Type == typeof(AnyPointerType) && type2.IsPointer)
{
return(true);
}
if (type2.Type == typeof(AnyPointerType) && type1.IsPointer)
{
return(true);
}
// likewise for any by ref
if (type1.Type == typeof(AnyByRefType) && type2.IsReference)
{
return(true);
}
if (type2.Type == typeof(AnyByRefType) && type1.IsReference)
{
return(true);
}
// Native int can be convereted to any pointer type
if (type1.IsPointer && type2 == TypeOnStack.Get <NativeIntType>())
{
return(true);
}
if (type2.IsPointer && type1 == TypeOnStack.Get <NativeIntType>())
{
return(true);
}
if ((type1.IsPointer || type1.IsReference) && !(type2.IsPointer || type2.IsReference))
{
return(false);
}
if ((type2.IsPointer || type2.IsReference) && !(type1.IsPointer || type1.IsReference))
{
return(false);
}
if (type1.IsPointer || type1.IsReference)
{
return(type1.Type.GetElementType() == type2.Type.GetElementType());
}
var t1 = type1.Type;
var t2 = type2.Type;
// The null type can be assigned to any reference type
if (t1 == typeof(NullType) && !TypeHelpers.IsValueType(t2))
{
return(true);
}
if (t2 == typeof(NullType) && !TypeHelpers.IsValueType(t1))
{
return(true);
}
t1 = Alias(t1);
t2 = Alias(t2);
return(ReallyIsAssignableFrom(t1, t2));
}
private static bool ReallyIsAssignableFrom(Type t1, Type t2)
{
if (t1 == t2)
{
return(true);
}
if (t1 == typeof(OnlyObjectType))
{
if (t2 == typeof(object))
{
return(true);
}
return(false);
}
// quick and dirty base case
if (t1 == typeof(object) && !TypeHelpers.IsValueType(t2))
{
return(true);
}
// you have to box in this case
if (t1 == typeof(object) && TypeHelpers.IsValueType(t2))
{
return(false);
}
var t1Bases = GetBases(t1);
var t2Bases = GetBases(t2);
if (t2Bases.Any(t2b => TypeOnStack.Get(t1).IsAssignableFrom(TypeOnStack.Get(t2b))))
{
return(true);
}
if (TypeHelpers.IsInterface(t1))
{
var t2Interfaces = (LinqArray <Type>)t2.GetInterfaces();
return(t2Interfaces.Any(t2i => TypeOnStack.Get(t1).IsAssignableFrom(TypeOnStack.Get(t2i))));
}
if (TypeHelpers.IsGenericType(t1) && TypeHelpers.IsGenericType(t2))
{
var t1Def = t1.GetGenericTypeDefinition();
var t2Def = t2.GetGenericTypeDefinition();
if (t1Def != t2Def)
{
return(false);
}
var t1Args = t1.GetGenericArguments();
var t2Args = t2.GetGenericArguments();
for (var i = 0; i < t1Args.Length; i++)
{
if (!TypeOnStack.Get(t1Args[i]).IsAssignableFrom(TypeOnStack.Get(t2Args[i])))
{
return(false);
}
}
return(true);
}
try
{
return(t1.IsAssignableFrom(t2));
}
catch (NotSupportedException)
{
// Builders, some generic types, and so on don't implement this; just assume it's *no good* for now
return(false);
}
}